Question for Engine Builders
RPM vs Cost

At what RPM limit would you say the cost of building a motor really starts to make a jump? Not looking a F1 type stuff here, just for motors used for short track racing. Maybe there's more then one step but where are the point that component or build cost hit the next level.

You have to learn the rules of the game. And then you have to play better than anyone else.

Does it really matter? Not being a smart-ass seriously asking. I understand that the actual cost would be different depending on the rules. However I am mainly thinking that the cost jumps would be due to rotating assembly upgrades required, but I'm not an engine builder so I my be overlooking things that is why I asked. I was kind of thinking along the lines of up to X RPM stock components can be used, then at Y RPM you need extra machining and balancing, then at Z RPM you have to upgrade to high end components. I may be over simplifying.

To narrow it down what I am trying to use this info for at this time would be a stock iron block, iron head, stock car type motor. It would also be a dirt. Does the surface really matter if the engine is seeing the same RPM?

You have to learn the rules of the game. And then you have to play better than anyone else.

In my opinion, RPM is the single biggest adjustment you can make to save money.

500 cubic inch cranks rods and pistons dont really cost more than 331 cubic inch (maybe less if they arent mega light) while the valvetrain will cost a lot less.

If I were making the rules there would be a 6200 rpm chip and rules about the connectors on your spec ignition box. The track will have to the authority to swap your ignition box and chip whenever they see fit.

I like Gavin's idea. I'm not an engine builder, but I owned cars for five different teams at one point in time. We made a sincere effort to keep our engines from turning more than 6400 RPM, and rarely had engine failures. I knew guys that were consistently running 7500 and more who replaced engines every few weeks. I used nothing special, just decent quality stuff. We lost an engine at Owosso that was running its fourth season with only a refresh kit tossed in. We were able to salve virtually all of the internal parts except the block. My big 'secret' was to call Crane and explain what we were going to do at what weight on what kind of track, etc, etc, etc. They recommended a cam that cost me $100 and it was a snappy lil thing.

Thanks for the input and I'm happy to see some of these number coming in the lower 6000's as being a viable race engine. I feel if something could be done to get the rpm and in turn the gearing down on cars it could be a real cost saver. Not just in the engine but wear and tear on the whole drive train.

You have to learn the rules of the game. And then you have to play better than anyone else.

Unhooking the cars would save me a lot of money. I used to do great on 450HP motors because that's what the tire could handle. Now I need to build another 600+HP motor if I want to keep racing on the tire we currently use. I like the RPM chip concept, however I believe that if we did it with tires, then we wouldn't have reason to add any rules. Problem is nobody wants to actually have to drive the racecar anymore...Racers want a car that's extra hooked up...and that's really the #1 thing that's hurting us.... Groups of drivers pushing for opened up rules, and they cast out anyone who doesn't agree with them... It's easy to see why we are where we are. Everything is controlled by a group of people who all think the same way and it's very counter-productive to where we actually need to go.

Have a great day.

Mike

I do it because I can. I can because I want to. I want to because you said I couldn't.

Yes, racing is all about traction/grip and the number one item that determines that is the tire. It is also probably the largest weekly expense for a lot of teams (I'm guessing even more so on asphalt). One thing that all racers have in common is that need for speed and that makes us our own worst enemy. The more grip we can get the more hooked up the car is the faster we can go. Isn't that the point after all? However in the pursuit of more speed comes the urge to push for rule changes that allow us to go faster and in turn add expense until we kill the class.

So yes I agree that the tire selection has a major role in saving cost and I would say that would be enough by its self if not for two factors.

The first is nothing more than a perceived advantage. For some reason there is a prevailing perception out there that if someone has a high dollar big horsepower motor they're going to beat you. I've proven this wrong most of the races I've ran in the street stocks, but what is has always been the first question I get asked after a race when I'm pulling away from someone on corner exit? "What have you got in that thing?" or simply a statement of "You've really got some power in that thing". Then I usually get the BS call or just a shake of the head in disbelief when I tell them honestly what I have. However what they don't take into account was the speed difference started sometimes as early as corner entry and just shows up the most down the straight. It makes it much easier to pull away from someone accelerating down the straight when you already had a speed advantage at the start. However some just can't seem to get past the idea that more horsepower (beyond what you can hook up) is the answer.

The second factor is less to do with horsepower and more to do with gearing. While they are both related when it comes to putting power to the track there will still be that point in the acceleration where traction allows the shorter gearing to out accelerate a taller gear and it is amplified in heavy cars. So as long as your engine can handle the rpm at the end of the straight a shorter gear is an advantage. For the longest time I didn't tend to believe that this was true and thought it completely foolish to spin the motor as high as some were. Until I had an opportunity to run two very similar powered engines with different rpm limits and resulting different gearing in the same car. Now if you take away enough grip from the cars maybe this part mostly goes away, but Iím not sure it does completely.

So in my opinion (which might not be worth much) if you could limit the traction with a tire that lasts and limit the rpm the engines turn you should be able to keep costs down. There are still going to be those that spend big, but hopefully you could get to a rules package that you donít have to in order to compete.

You have to learn the rules of the game. And then you have to play better than anyone else.